Cyclohexane diamine tetraacetate

The treatment of complex ion equilibria in solution is analogous to the treatment of weak acids. One of the best known chelators is the well-known EDTA (ethylene diamine tetraacetic acid). The metal stability constants for EDTA are very high, which indicates strong complexes. Various other compounds are available with high metal-stability constants for agricultural or environmental uses. Some of the more important ones are DPTA (diethylene triamine pentaacetic acid), CyDTA (cyclohexane diamine tetraacetic acid), EDDA [ethylene diamine di (0-hydroxyphenyl acetic acid], or Chel-138. 

The following abbreviations for the ligands are used throughout the paper CyDTA = trans-cyclohexane diamine tetraacetate, EDTA = ethylene-diamine tetraacetate, 1.3-PDTA = 1.3-propanediaminetetraacetate, EDDaDp = ethylenediamine-N,N -dipropionate-N,N -diacetate, IDA = iminodiacetate, MIDA = N-methyl-iminodiacetate, EIDA = N-ethyl-iminodiacetate, n-PIDA = N-n-propyl-iminodiacetate, n-BIDA = N-n-butyl-iminodiacetate. 

Preparation of TISAB II The mixture of 4.5 g of cyclohexane 1,2 diamine N,N,N, N -tetraacetic acid (CDTA), 58 g sodium chloride, 57 cm glacial acetic acid, and 500 cm water are stirred while 120 cm of 5 M sodium hydroxide solution is added slowly. After complete dissolution, the pH is adjusted to the range of 5.0-5.5 with sodium hydroxide, and washed in 1 dm volumetric flask and filled up to the mark with deionized water. This solution can be stored for a longtime in plastic bottles. 

Potentiometric Cl- and F-measurement As been demonstrated [62], chloride and fluoride ion concentration of potable water samples can be determined simultaneously with chloride and fluoride ion-selective electrodes built in a special flow-through apparatus. Using the sequential injection principle, cyclohexane-l,2-diamine-N,N,N, N -tetraacetic acid, TISAB, and Ag/AgCl reference electrode, water samples of 0.2 cm volume could be analyzed in the range of 20—500 pg/cm (chloride) and 0.5—200 pg/cm (fluoride) concentration. 

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